The pulmonary inflammatory response and pulmonary dysfunction after cardiopulmonary bypass is a major problem in patients undergoing cardiac surgery. Propofol has anti-inflammatory and immunomodulatory properties which may attenuate this response. Thirty patients undergoing cardiopulmonary bypass were randomly assigned to receive saline (control group) or propofol (propofol group). Pulmonary thoracic compliance, respiratory index, malondialdehyde and interleukin-8 concentrations and intrapulmonary polymorphonucleocyte sequestration were measured at pre-bypass and 5, 30, 60, 90 and 120 min after unclamping the aorta. Plasma levels of interleukin-8, malondialdehyde and the respiratory index increased and reached peaks 30 min after unclamping in both groups. However, in the propofol group the increases were less than in the control group (p < 0.01). Intrapulmonary polymorphonucleocytes sequestration in the propofol group was less than in the control group 5 min after unclamping (p < 0.0001). Pulmonary thoracic compliance decreased significantly after unclamping in both groups, but the reduction was less in the propofol group (p < 0.01). These findings suggest that propofol administered during bypass could reduce the severity of pulmonary dysfunction.